In medicine, laser light is used, inter alia, for the controlled coagulation or vaporization of tissue, thereby removing it. Thus, a special advantage of laser light of a certain wavelength resides in its transferability by way of flexible light guides; this permits working with laser light under optical control with an endoscope even at sites in the human body difficult to reach otherwise. Thus, in many clinics laser endoscopy is already being used routinely in gastroenterology, urology, neurosurgery, pulmonology, etc. for the removal of benign and malignant tissue.
Now if, for example, in the region of the gastrointestinal tract a "tube-like" passage is constricted by the growth of a tumor or other causes, it can often be opened up again by means of laser light under endoscopic control. Here, advanced constrictions extending over a long distance (stenoses) present special difficulties.
For the upper digestive tract, several procedures are known:
If a stricture is endoscopically not passable, it is opened up by means of laser light in the forward direction. The natural course of the passage is often difficult to recognize especially in the case of extended malignant tumor stenoses due to irregular growth of the tumor, invading tissue neoformation along with crater-like tumor collapse, so that often a deviation from the natural passage course and opening of the wall by the laser beam occurs. According to specialists, the risk of perforation is as much as 30%.
A second method for the upper digestive tract consists in a combined laser and bougienage therapy, in which in case of endoscopic impassibility of a stricture the latter is first expanded by bougienage, the endoscope is guided through the stricture, and then the stenosis is "lasered open" by slowly retracting the endoscope from distal to proximal.
In many endoscopically reachable places, as for instance in the lower digestive tract, in the bronchial tract or in neurosurgery, however, bougienage is hardly possible--it is usually unpleasant and painful for the patient--and subject to a certain risk of perforation, and it usually requires several sessions on different days, thereby additionally lengthening the stay in the hospital.